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Introduction

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BASICS IN MINERAL PROCESSING

“The practice of minerals processing is as old as human civilisation. Minerals andproducts derived from minerals have formed our development cultures from theflints of the Stone Age man to the uranium ores of Atomic Age”.

The ambition with this handbook, “Basics in Mineral Processing Equipment”, is notto give a full coverage of the subject above.

The intention is to give technicians involved in mineral operations practical anduseful information about the process equipment used, their systems and operationalenvironment.

The technical data given are basic, but will increase the understanding of theindividual machines, their functions and performances.

Basic DefinitionsIt is important to know the definitions of mineral, rock and ore as they representdifferent product values and partly different process systems

Mineral Rock Ore

Na+

Ca2+ Si4+ O2-

CO22- Fe2+ OH-

Heat Pressure Heat Pressure Heat PressureDeformation Chemical

activity

“Natural components of “Compounds of minerals” “Rocks containing minerals orchemical elements” metals which can be recovered with profit”

Artificial minerals

“Man made” minerals are not minerals by definitions. But from processing point ofview they are similar to virgin minerals and are treated accordingly (mainly inrecycling processes).

Slag Concrete Mill scale Glass & Ceramics

Min

eral

Min

eral

Min

eral

Rock

Rock

Rock

Rock

Ore

Ore

Ore

SiO

2

Ca

Co 3

Fe2

O3

AbrasivesCorundumQuartzDiamond a.o.

GlassQuartzFeldsparCalciteDolomite a.o.

PlasticCalciteKaolinTalcWollastoniteMica a.o.

RefractoriesWollastoniteCalciteDolomiteCorundum a.o.

CeramicsQuartzKaolinFeldspar a.o.

FertilisersPhosphatePotashCalciteDolomite a.o.

Fillers and PigmentBariteBentoniteCalciteDolomiteFeldsparTalc a.o.

RefractoriesWollastoniteCalciteDolomiteCorundum a.o.

Base MetalsCopperLeadZinc a.o.

Light MetalsAluminiumMagnesiumTitanium

Precious MetalsGoldSilverPlatinum a.o.

Rare MetalsUraniumRadiumBeryllium a.o.

Alloying MetalsChromiumVanadiumMolybdenumTungstena.o.

Minerals by Value

CoalsOil shale(Oil sand)

Concrete ballastAsphalt ballastRock fillIndustrial sanda.o.

Aggregate, Sand & Gravel

Non-ferrous Ferrous Alloy

Industrial Minerals Mineral Fuels

Minerals

Rock Ores

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BASICS IN MINERAL PROCESSING

The Process Frame of MineralsThe goal in mineral processing is to produce maximum value from a given rawmaterial. This goal can be a crushed product with certain size and shape ormaximum recovery of metals out of a complex ore.The technologies to achieve these goals are classical, complementary and welldefined.Below they are presented in the Process Frame of Minerals, classified accordingto their interrelations in product size and process environment (dry or wet).

Drilling (and blasting) is the technology of achieving primary fragmentation of“in situ” minerals. This is the starting point for most mineral processes with theexception of natural minerals in the form of sand and gravel.

Crushing and screening is the first controlled size reduction stage in theprocess. This is the main process in aggregate production and a preparationprocess for further size reduction.

Grinding is the stage of size reduction (wet or dry) where the liberation size forindividual minerals can be reached. By further size reduction filler (mineralpowder) is produced.

Slurry processing includes the technologies for wet processing of mineralfractions.

Pyro processing includes the technologies for upgrading of the mineral fractionsby drying, calcining or sintering.

Materials handling includes the technologies for moving the process flow (dry)forward by loading, transportation, storage and feeding.

Compaction of minerals includes the technologies for moving and densifyingminerals by vibration, impaction and pressure, mainly used in constructionapplications.

Size 1m 100 mm 10 mm 1 mm 100 micron 10 micron 1 micron8

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BASICS IN MINERAL PROCESSING

In 1813 an Austrian geologist, Mr. Mohs, classified minerals according to their individual hardness.

Crushed by a finger nailScratched by a finger nailScratched by an iron nailEasily scratched by a knifeScratched by a knifeHardly scratched by a knifeScratches glassScratched by quartzScratched by a diamondCannot be scratched

Graphite, Sulphur, Mica, Gold Dolomite Magnesite Magnetite Granite, Pyrite Basalt Beryl

Mineral Processing and HardnessAll deposits of minerals, rock or ores have different hardness depending on thechemical composition and the geological environment.

Mohs numbers are a simple classification:

Size and HardnessAll operations have different process environments due to mineral hardness andsize range. It is important to know in which “range” we are operating as this willaffect many process parameters, (wear rate, uptime, operation costs etc.).Size and hardness together give interesting information.

In operation we naturally need more information about our feed material.See information on work index and abrasion index, section 3 page 2.

1. Talc2. Gypsum3. Calcite4. Fluorite5. Apatite6. Feldspar7. Quartz8. Topaz9. Corundum

10. Diamond

10

9

8

7

6

5

4

3

2

1

HardnessMohs

INDUSTRIALMINERALS

ROCK

BALLAST

SAND

METALLICMINERALSCONSTRUCTION MATERIALS

AGGREGATES

COARSE FILLER FINE FILLER

SAND

MICRO FILLER

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The Stress Forces of Rock MechanicsBeside size and hardness, the classical stress forces of rock mechanics are thefundamentals in most of what we do in mineral processing. They guide us inequipment design, in systems layout, in wear protection etc. They are alwaysaround and they always have to be considered.

Tensile Compression

Impaction Shearing

Attrition